Antigenotoxic potential of plant monoterpenes linalool, myrcene and eucalyptol against IQ- and PhIP- induced DNA damage

: Nutrition is recognised as one of the major factors that can influence the development of cancer. Heterocyclic amines formed during the cooking of meat are genotoxic carcinogens and consumption of meat positively correlates with certain types of human cancer. On the other hand, it has been reported that many plant components reduce the genotoxic activities of carcinogens, including HCAs. In this study we investigated the antigenotoxic potential of the monoterpenes linalool, myrcene and eucalyptol against two food-borne carcinogens: 2-amino-1-methyl-6-phenylimidazo[4-5- b ]pyridine (PhIP) and 2-amino-3-methylimidazo[4,5-f]-quinoline (IQ). The study was performed by the comet assay method in metabolically active HepG2 human hepatoma cells. In addition, the lipid peroxidation TBA assay was used to determine the anti-oxidative potential of these monoterpenes. To evaluate the antigenotoxic potential, cells were treated simultaneously with 0.01, 0.1 or 1 μg/mL of monoterpenes and either 90 μmol/LPhIP or 0.75 mmol/L IQ. The DNA damage induced by PhIP was reduced significantly (by 40-63%) by each of the three monoterpenes, while inhibition of IQ-induced DNA damage was less efficient (12-26% reduction) and limited to myrcene and eucalyptol. Lipid peroxidation was significantly inhibited by linalool and myrcene, with IC 50 values of approximately 30 μg/mL and 300 μg/mL, respectively. Eucalyptol showed only weak antioxidant activity (15% inhibition at 500 μg/mL). Taking into account the fact that reactive oxygen species (ROS) are formed during metabolic processing of PhIP, we assume that more efficient protection against PhIP-induced DNA damage was probably due to antioxidative activity of the monoterpenes or their metabolites, but the ability to interfere with metabolic activation of PhIP and IQ could also be involved.